1. Field of the Invention
The present invention relates to a system search method in a communication system. More particularly, the present invention relates to a mobile terminal and method for performing a system search that minimizes battery consumption after a system loss.
2. Description of the Related Art
In general, to establish a communication channel, a mobile terminal selects a base station of a mobile communication system for synchronization, and acquires system information from the selected base station. The mobile terminal notifies the base station of its location and registration information using the acquired system information, establishes the communication channel and receives call-related services.
Here, the term “system” refers to a communications infrastructure that is managed by a mobile network operator to provide mobile communication services to mobile terminals. The system may use analog technology, digital cellular technology, Personal Communications Service (PCS) technology and the like.
When a system loss occurs, owing to a loss or failure of the communication channel with a base station, a mobile terminal performs a system search according to a preset system search parameter. That is, the mobile terminal attempts to reestablish the same or another communication channel with a base station by searching for a system. According to the preset system search parameter, the mobile terminal performs an initial system search for a first search time period. If no system is found during the first search time period, the mobile terminal transitions to a power-saving mode (e.g. sleep mode) and then performs a system search for a second search time period. The second search time period corresponds to a preset search period composed of the duration of the power-saving mode and the duration of the system search. This second search time period may be repeated if necessary.
According to a conventional search parameter, the first search time is set to be longer than the second search time. Hence, even if no system is found during the first search time, battery power is still rapidly consumed. Alternatively, if the first search time is set to be shorter, battery power can be saved. However, the system search is more likely to be unsuccessful, and service quality of the mobile communication system can be degraded.